Created
April 14, 2012 14:09
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Subscribe to MQTT messages in browser using HTML5 Server-Sent Events
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| #!/usr/bin/env ruby | |
| require 'rubygems' | |
| require 'eventmachine' | |
| require 'em-mqtt' | |
| require 'sinatra/base' | |
| require 'thin' | |
| class WebApp < Sinatra::Base | |
| set :server => 'thin' | |
| enable :inline_templates | |
| def self.connections | |
| @connections ||= [] | |
| end | |
| get '/' do | |
| erb :index | |
| end | |
| get '/stream' do | |
| content_type 'text/event-stream' | |
| stream :keep_open do |out| | |
| WebApp.connections << out | |
| out.callback { WebApp.connections.delete(out) } | |
| end | |
| end | |
| end | |
| class MyConnection < EventMachine::MQTT::ClientConnection | |
| attr_accessor :connections | |
| def receive_msg(packet) | |
| connections.each do |c| | |
| c << "data: #{packet.topic}: #{packet.payload}\n\n"; | |
| end | |
| end | |
| end | |
| EventMachine.run do | |
| MyConnection.connect('test.mosquitto.org') do |c| | |
| c.subscribe('#') | |
| c.connections = WebApp.connections | |
| end | |
| WebApp.run! | |
| end | |
| __END__ | |
| @@ layout | |
| <html> | |
| <head> | |
| <title>MQTT EventSource</title> | |
| <meta charset="utf-8" /> | |
| <script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script> | |
| </head> | |
| <body><%= yield %></body> | |
| </html> | |
| @@ index | |
| <pre id='messages'></pre> | |
| <script> | |
| var es = new EventSource('/stream'); | |
| es.onmessage = function(e) { | |
| $('#messages').append(e.data + "\n"); | |
| $('html, body').scrollTop($(document).height()); | |
| }; | |
| </script> |
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At one point I was going to make the main mqtt gem powered by EventMachine, but I have had such trouble with debugging it, that I thought it was a bad idea.
Love EventMachine and the ideas behind it, but it can be a real pain.